This invention relates to hearth arrangements for cold hearth refining.
Cold hearth refining of materials such as metal alloys is normally carried out in an evacuated melt chamber in which a hearth is mounted in position to receive the material to be refined and to supply molten refined material to an outlet arrangement such as an ingot mold. The hearth, which is conventionally supported on an open base arrangement receives energy to melt the material to be refined from electron beam or plasma sources near the top of the evacuated melt chamber. To cool the walls of the hearth, the hearth contains internal water ducts and water supply and return lines are connected from the side wall of the evacuated chamber to the side of the hearth.
Such conventional arrangements expose the water circulation pipes to potential damage from electron beam or plasma arc energy sources intended to be directed toward the material in the hearth and to mechanical damage from moving of objects within the melt chamber during set up and shut down. They also allow accumulation of loose raw material on the floor of the chamber adjacent to and beneath the hearth which must be removed in order to maintain a clean melt chamber.